Method and apparatus for testing material integrity

1. A testing apparatus for detecting defects in a test object, comprising:

an electrical conductor extending in a generally linear direction, wherein the electrical conductor is configured to route current in a generally transverse direction with respect to a longitudinal axis of the test object; and

a sensing device located a distance from the electrical conductor and configured to detect a magnetic field generated in response to current routed through the electrical conductor.

2. The testing apparatus as recited in claim 1 , wherein the electrical conductor is substantially a flat electrical conductor.

3. The testing apparatus as recited in claim 1 , comprising a carrier structure configured to direct the electrical conductor in a testing direction along a path of travel generally corresponding with the longitudinal axis of the test object.

4. The testing apparatus as recited in claim 3 , wherein the carrier structure is configured to travel along a rail.

5. The testing apparatus as recited in claim 1 , wherein the electrical conductor is configured to receive direct current (dc) power.

6. The testing apparatus as recited in claim 1 , wherein the electrical conductor is configured to be disposed outboard of an external surface of the test object.

7. The testing apparatus as recited in claim 1 , comprising an actuation mechanism configured to position the electrical conductor with respect to the test object.

8. The testing apparatus as recited in claim 1 , wherein the electrical conductor is configured to receive alternating current (ac) power.

9. A testing apparatus for detecting defects in a rail of a railroad transportation system, comprising:

an electrical conductor extending in a generally linear direction and configured to route current in a generally transverse direction with respect to a longitudinal axis of the rail;

a carrier structure configured to direct the electrical conductor in a testing direction along a path of travel generally parallel to the longitudinal axis of the rail and external to the rail; and

a magnetic-field sensor located a distance from the electrical conductor and configured to detect a magnetic field generated in response to current routed through the electrical conductor, wherein the magnetic-field sensor travels behind the electrical conductor during movement of the electrical conductor in the testing direction.

10. The testing apparatus as recited in claim 9 , wherein the electrical conductor is configured to be disposed adjacent to the rail during testing.

11. The testing apparatus as recited in claim 9 , wherein the magnetic-field sensor comprises at least one of a Hall effect sensor and a giant magneto-resistive (GMR) sensor.

12. The testing apparatus as recited in claim 9 , comprising a gauss-meter for measuring signals from the magnetic-field sensor.

13. The testing apparatus as recited in claim 9 , comprising processing circuitry configured to provide signals indicative of a defect in the rail in response to communications from the magnetic-field sensor.

14. The testing apparatus as recited in claim 13 , further comprising a display configured to visually indicate a defect in the rail in response to communications from the processing circuitry.

15. The testing apparatus as recited in claim 9 , further comprising wireless communication circuitry configured to transmit and receive information from the magnetic-field sensor in accordance with a wireless protocol.

16. The testing apparatus as recited in claim 9 , further comprising network communication circuitry configured to communicate with a remote location via a network.

17. The testing apparatus as recited in claim 9 , comprising an alternating current (ac) power source configured to provide ac current to the electrical conductor.

18. The testing apparatus as recited in claim 17 , wherein the ac power source comprises a pulse width modulated power source.

19. The testing apparatus as recited in claim 9 , comprising a direct current (dc) power source configured to provide dc current to the electrical conductor.

20. A method for detecting defects in a test object, comprising the acts of:

routing electrical current in a direction generally transverse to a longitudinal axis of a test object via an electrical conductor, such that the electrical current induces eddy currents in the test object; and

sensing at least one magnetic field generated in response to the routed electrical current at a distant location from the electrical conductor.

21. The method as recited in claim 20 , comprising displacing the electrical conductor in a testing direction generally parallel to the longitudinal axis of the test object along an external surface of the test object.

22. The method as recited in claim 20 , comprising the acts of:

measuring the at least one magnetic field using a measuring device; and

processing a first set of signals from the measuring device to develop a second set of signals indicative of a defect in the test object.

23. The method as recited in claim 20 , comprising sensing the at least one magnetic field that is generated in a direction generally transverse to the longitudinal axis of the test object.

24. The method as recited in claim 20 , comprising measuring the magnetic field in a direction generally transverse to the longitudinal axis of the test object.

25. A method for detecting defects in a rail, comprising the acts of:

routing electrical current in a direction generally transverse to a longitudinal axis of the rail via a conductor, such that the electrical current induces eddy currents in the rail;

displacing the conductor in a testing direction generally parallel to the longitudinal axis of the rail; and

sensing magnetic field at a location behind the conductor during motion of the conductor in the testing direction.

26. The method as recited in claim 25 , comprising routing an alternating current (ac) through the conductor.

27. The method as recited in claim 25 , comprising routing a direct current (dc) through the conductor.

28. The method as recited in claim 25 , comprising:

amplifying a first set of signals indicative of the magnetic field using an amplifier;

measuring the first set of signals via a measuring device; and

processing the first set of signals from the measuring device to develop a second set of signals indicative of a defect in the rail.

29. A method of detecting defects in a test object, comprising:

sensing a magnetic field at a location behind a substantially flat conductor inducing current in the test object in a direction generally transverse to a longitudinal axis of the test object, the magnetic field propagating along an external surface of the test object in a direction generally parallel to the longitudinal axis of the test object; and

generating a signal indicative of a defect in the test object based on the sensed magnetic field.

30. The method as recited in claim 29 , further comprising correlating the generated signal with a type of defect in the test object.

31. The method as recited in claim 29 , comprising sensing a magnetic field at a location behind the substantially flat conductor inducing current in a rail and generating a signal indicative of a defect in the rail.

32. The method as recited in claim 31 , comprising correlating the generated signal with a type of defect in the rail.

33. A testing apparatus for detecting defects in a test object, comprising:

means for routing current in a direction generally transverse to a longitudinal axis of the test object;

means for directing the means for routing current in a direction generally parallel to the test object; and

means for sensing a magnetic field generated by induced current in the test object at a location behind the means for routing current.

34. A computer program for testing an object, the computer program being disposed on one or more tangible media, comprising:

code for receiving data indicative of a magnetic field generated in response to current routed through a flat electrical conductor in a direction generally transverse to a longitudinal axis of the object, wherein the magnetic field is at a distance from the flat electrical conductor; and

code for estimating a defect in the object based on the received data.